Hi! For example, edges next to each other cannot snap? Thanks in advance.
It depends on the direction you’re coming from. If it’s two outer edges that aren’t overlapping, then Acorn does not currently snap those. But if the images are overlapping, then they can snap together. You’ll need to make sure it’s turned on for the image though, via the View ▸ Guides and Grids ▸ Snap to Shapes menu item. You can also turn it on for all new images, via the Guides Preferences tab.
Hope that helps,